(poster) Photoelectron Emission Spectroscopy Analysis on the Degradation of AlO_x Surface Passivation under Damp Heat and Light Soaking

Atomic layer deposited aluminium oxide is the material of choice for the surface passivation of silicon, especially in the case of nanotextured light absorbing surfaces. The excellent passivation performance of aluminium oxide is based on its good interfacial properties with silicon as well as the high negative charge of the passivating film. Stable surface passivation performance is vital for commercial photovoltaic devices making use of the nanostructured silicon surfaces, such as sensitive photodetectors and high-efficiency solar cells. Recently, we showed that damp heat exposure and light soaking can cause significant degradation of aluminium oxide surface passivation, but the exact degradation mechanisms require further studies. In this work, we investigate how damp heat exposure and light soaking affect aluminium oxide passivation films using Photoelectron Emission Spectroscopy (PES). Our results showed no differences between the undegraded and degraded samples regarding the positions or the area of the peaks corresponding to Al2p, Si2p or Al2s orbitals. However, significant differences were observed in the areas of the peaks corresponding to O1s orbitals close to 533 eV. These findings indicate that damp heat and light soaking conditions primarily affect the bonding of oxygen in the aluminium oxide films.